EXPERIMENTAL STUDIES ON MALIGNANT FIBROUS HISTIOCYTOMAS .2. ULTRASTRUCTURE OF MALIGNANT FIBROUS HISTIOCYTOMAS INDUCED BY 4-(HYDROXYAMINO)-QUINOLINE 1-OXIDE IN RATS

  • 1 January 1983
    • journal article
    • research article
    • Vol. 48  (2) , 187-198
Abstract
The ultrastructures of 6 subcutaneous and 6 bone malignant fibrous histiocytomas (MFH) induced in rats by local application of the carcinogen, 4-(hydroxyamino)-quinoline 1-oxide (4-HAQO) were studied. The MFH could be classified histologically into 3 subtypes: of the 6 subcutaneous MFH, 4 were fibrous, 1 was giant cell, and 1 was myxoid; of the osseous MFH, 3 were fibrous, 1 was giant cell, and 2 were myxoid. Five different types of cells were found in the MFH: fibroblast-like cells, histiocyte-like cells, undifferentiated cells, xanthomatous cells, and multinucleated giant cells; the xanthomatous cells and multinucleated giant cells were probably derived from histiocyte-like cells. Fibroblast-like cells predominated in storiform areas of the fibrous subtype; histiocyte-like cells and undifferentiated cells predominated in the giant cell subtype; intermediate cells predominated in the myxoid subtype. Acid phosphatase activity was found in lysosomes and myelin figures of the histiocyte-like cells in fibrous type MFH. The giant cell subtype of bone MFH has been transplanted serially into syngeneic rats and is now at the 17th generation. Transplantability exceeded 80%; doubling time was 3.8-6.1 days. Until the 3rd generation, the histology of the original tumor was retained; from the 4th generation, giant cells and xanthoma cells were no longer observed, and the tumor was composed mainly of undifferentiated cells. MFH induced in the rat by 4-HAQO have an ultrastructure similar to human MFH and the giant cell subtype transplanted serially is gradually transformed with a probable selection of stem cells and undifferentiated cells.